Marijuana businesses raided by federal agents in the Denver metro-area on Thursday are being investigated for possible links to Colombian drug cartels, sources told The Denver Post on Friday.

The two sources, who have knowledge of the investigation, spoke on condition of anonymity.

A search warrant obtained by The Denver Post included 10 “target subjects” who were owners of businesses or people connected to marijuana dispensary businesses.

Authorities from the U.S. Department of Justice and and Internal Revenue Service raided at least a dozen businesses and two homes throughout the Denver metro area on Thursday, serving search and seizure warrants.

Agents, some of them wearing black ski masks, seized boxes of records and piles of medical marijuana.

Federal officials wouldn’t give specific reasons for the raids, other than to say one of eight federal concerns around marijuana have potentially been violated. Those concerns include trafficking marijuana outside of states where it has been legalized and money laundering.

One of the “target subjects” identified in the search warrant, Denver attorney David Furtado, denies any wrongdoing, according to Furtado’s lawyer, Stanley Marks.

A law enforcement officer walks past a pile of marijuana seized during a raid at Swiss Medical Industries in Boulder, Colo., Thursday, Nov. 21, 2013. The U.S. Attorney’s Office says the Internal Revenue Service’s criminal investigations unit and the Drug Enforcement Administration are involved. Spokesman Jeff Dorschner says that the operation is in accordance with recent Justice Department’s guidance on marijuana enforcement. (AP Photo/The Daily Camera, Mark Leffingwell )